(CI for Mean) The pH levels of a random sample of 16 chemical mixtures from a processwere measured, and a sample mean ?x = 6.861 and a sample standard deviation s = 0.440 wereobtained. The scientists presented a confidence interval (6.668, ?) for the average pH level ofchemical mixtures from the process. What is the confidence level of this confidence interval?Suppose the pH level of the chemical mixture is normally distributed.